Holder unit for optical instrumental analysis system

ABSTRACT

A combination teaching aid and modular instrumental analysis system in which a plurality of modules are provided, each having a separate function, and in which the different modules are adapted to be placed together in different combinations to provide different optical analysis instruments. The modules include a light source for providing light, a detector module for receiving light which has been exposed to a sample compartment module which receives one or more samples to be analyzed, and may include display means in the form of a meter or the like for reading the output of the detector module. The combination may also include a monochromator unit for providing substantially monochromatic light, and a filter module which is adapted to contain one or more filters through which a light beam may be passed for obtaining a beam of desired frequency. Different arrangements of the various modules will produce a spectrophotometer, a filter photometer, or a nephelometer. The described module units are arranged so that at least some of them may be disposed on a base and optically aligned by means of combination adjusting and clamping means, so that the units may be thereafter moved, or replaced as desired without affecting the alignment thereof. The described units are constructed and arranged so that all the significant operational and functional properties of each module may be directly observed by the student. Therefore, each module is adapted to perform a minimum number of functions, and the modular concept and the construction features are used as a teaching aid used to emphasize the relation between various systems of optical instrumental analysis. The filter compartment module and the sample compartment module include holder means for holding light filters or sample units, and the holder unit is constructed so as to facilitate interchange of sample holders and filter units, and to be adapted for use without change to perform different functions in different instrumental combinations.

United States Patent [191 Boostrom et al.

1*Apr. 23,1974

[ HOLDER UNIT FOR OPTICAL INSTRUMENTAL ANALYSIS SYSTEM [7 51 Inventors:Roy Edward Boostrom, Elmhurst;

Arman Mandel], Chicago; Lewis Malter, Morton Grove, all of I11. [73]Assignee: Sargent-Welch Scientific Company,

Skokie, Ill.

[ Notice: The portion of the term of this patent subsequent to Oct. 31,1989, has been disclaimed. I

[22] Filed: Oct. 30, 1972 [21] Appl. No.: 301,850

- Related U.S. Application Data [60] Continuation of Ser. No. 871,249,Nov. 3, 1970, Pat.

No. 3,701,603, which is a division of Ser. No.

694,517, Dec. 29, 1967, Pat. No. 3,554,648.

[52 .s.c|. 356/244, 356/246 51 Int. Cl. G01n21/16,G0ln 1/10 58 Field ofSearch 356/244, 246

[56] References Cited UNITED STATES PATENTS 5/1967 Shah 356/246 4/1970Ross et al.

10/ 1972 Boostrom et al. 356/246 OTHER PUBLICATIONS Instrumental Methodsof Analysis; Willard et al.; 1965; pp. 382 & 383.

Primary Examiner-Ronald L. Wibert Assistant ExaminerV. P. McGrawAttorney, Agent, or FirmLockwood, Dewey, Zickert &Alex

[57] ABSTRACT A combination teaching aid and modular instrumentalanalysis system in which a plurality of modules are provided, eachhaving a separate function, and in which the different modules areadapted to be placed together in different combinations: toprovidedifferent optical analysis instrumentsfThe modules include a lightsource for providing light, a detector module for Different arrangementsof the various modules will produce a spectrophotometer, a filterphotometer, or a nephelometer. The described module units are arrangedso that at least some of them may be disposed on a base and opticallyaligned by means of combination adjusting and clamping means, so thatthe units may be thereafter moved, or replaced as desired withoutaffecting the alignment thereof. The described units are constructed andarranged so that all the significant operational and functionalproperties of each module may be directly observed by the student.Therefore, each module is adapted to perform a minimum number offunctions, and the modular concept and the construction features areused as a teaching aid used to emphasize the relation between varioussystems of optical instrumental analysis.

The filter compartment module and thesample compartment module includeholder means for holding light filters or sample units, and the holderunit is constructed so as to facilitate interchange of sample holdersand filter units, and to be adapted for use without change to performdifferent functions in different instrumental combinations.

8 Claims, 27 Drawing Figures PATEMEDAPR 23 I974 118 O6 259 SHEET 3 OF 7LATENTEDAPRN I974 3806259 SHiET 6 [IF 7 HOLDER UNIT FOR OPTICALINSTRUMENTAL ANALYSIS SYSTEM This is a continuing application based onapplicants application Ser. No. 871,249, filed Nov. 3, 1970, now U. S.Pat. No. 3,701,603, which in turn is a divisional application based onapplication Ser. No. 694,517, filed Dec. 29, 1967, now U. S. Pat. No.;3,554,648.

BACKGROUND OF THE INVENTION 1. Field of the Invention The field of thepresent invention is that of modular instrumental analysis systems inwhich a plurality of separate modules are particularly adapted to bearranged to form a variety of different optical instrumental analysisunits, each of which instrument contains one or more common units. Thisapplication is a'division of Ser. No. 694,417, filed Dec. 29, 1967. Thepresent invention is useful, not only as a laboratory instrument, butalso as a teaching aid, since the design thereof is such that individualoperational or functional features or characteristics of each unit aremaintained separate from each other, and are constructed and ar-' rangedwithin the units so that the operation thereof may be readily observedby a student. The described modules are sufficient to create instrumentswhich will allow determinations to be made by nephelometry, colorimetry,turbidimetry or spectrophotometry.

The modular components include light source means, monochrometer meansfor breaking up light into monochromatic portions, a sample compartmentfor holding a plurality of samples,.or holding one individual sample, afilter compartment for accommodating means for holding one or more colorfilter units, and a detector unit for determining characteristics of alight beam transmitted thereto. In addition, the system includes a basefor supporting different modules, and each module contains supportingmeans which facilitate alignment thereof in regard to the other modules,since alignment of themodules is obviously desirable in any opticalinstrumental analysis system.

In addition, the invention includes specially designed components,particularly a novel holder unitfor holding optical filters as well assample containers, and the holder units are adapted to assist inobtaining rapid analysis and standarization as well as change offunction without change of mode of operation thereof, or change oflocation within the unit.

The system also includes a power supply unit, and visible display meansin the form of a meter or the like, which is adapted to be used with thedetector module in order to display the information received by thedetector unit.

2. Description of the Prior Art 1 Instruments such as those which may bemade by assembling the modules of the present invention in and, to acertain extent, the concept of modular construction of instrumentshaving common functional elements or components has been known. Inaddition, itis known that certain optical analysis instruments includecommon components, since such instruments depend on utilization of alight source and detection of one or more of the characteristics of abeam of light which is effective in some way by passage through, or byreflection or scattering from, a sample unit whose properties will insome way be indicated by the effect of an incident light beam thereon. l

Since the advent of reliable analysis instruments, it has beenincreasingly common in industry and other fields to perform chemicalanalysis by instrumental methods, and accordingly, there has been asubstantial demand for competent teaching in the area of instrumentalchemical analysis, and, as a corollary thereof, there has been a demandfor teaching aids which would simplify the task of instructing studentsin the fundamental similarities and differences in various analysistechniques as well as the basic theories underlying such systems.

Almost all commercially available analysis instru ments are designed toperform only one analytical operation, and, since many such insturmentsare sold competitively, they are normally designed having an object inmind of minimum cost, maximum compactness and with a view towardsruggedness and dependability, which norrnally implies that delicatecomponents thereof be shielded from dust, dirt and other contamination,and from the possibility of damage by handling and the like. Thus, thenormal analytical instrument used for optical analysis is not suited foruse as a teaching aid, since the manner of its operation is not readilyapparent from viewing the instrument itself, functional components beinggenerally hidden from view. l 0

Likewise, modular instrumental systems heretofore known have generallybeen designed withthe idea of economy as a primary purpose, andthedesign of such systems has emphasized minimum duplication of parts. Suchmodular instrument systems accordingly were not designed with the objectin mind of laying out the components in the logical manner in which eachoperation took place, but were generally designed with'the view thatsuch units should be made compact and, where possible, include singlecomponents which could be used to perform several functions in the sameinstrument.

Thus, the prior art has not heretofore disclosed a simple and economicalmodular system in which the parts may not only be assembled to makedifferent optical analysis instruments, but may be simply and accuratelyarranged, removed, placed into different combination, and replacedwithout the need for individual adjustment, and which systems alsopossess sufficient accuracy for classroom work, for use in an analyticallaboratory, or for industrial use. Thus, the present invention combinesthe accuracy of a'laboratory instrument at comparable cost, and alsoincludes special design features making possible great simplicity inhandling of filters and samples, as well as in handling of the modulescontaining the units, all in asystem which is expressly designed to beobserved and studied with relation to the theoretical bases underlyingthe operation of optical instrumental-analysis.

SUMMARY OF THE INVENTION present invention is to provide a modularinstrumenta-fi tion system which includes a plurality of modules whichmay be arranged in different combinations to provide differentinstruments.

Another object is to provide a modular system which includes means formounting and alignment which simplifies the disposition of various partsin desired relation to each other to make such instruments.

A further object is to provide a modular instrument system in which theoperations carried out by each module may be simply and readily observedby a student and be readily demonstrated by an instructor.

A further object is to provide a system in which a single detectormodule means may be used with a common display means for indicating thecondition of a system.

Another object is to provide a simplified means for holding samplecontainers and filter elements, so that such elements may be locked in adesired relation for standarization or observation, rotated to otherpositions, and held in place against rotation while being observed orcompared, and in which such holder is constructed and arranged to allowlight passage therethrough along two different axes.

Another object is to provide a plurality of modules wherein access maybe had to the interior thereof in a simple manner for study of thecomponents thereof,

Another object is to provide a modular instrument analysis and teachingaid system in which the components may be held together in variousassembled relationships by simple but effective means which do away withthe need for frequent adjustment.

The present invention accomplishes these objects, and others which areinherent therein, by providing a combination teaching aid and modularinstrument analysis system which includes a light source module forproducing light and which includes light emitting means therein, asample compartment for receiving I sample containers of a material to beanalyzed, a detector module for receiving light directed from the lightsource into the sample compartment and thence into the detector module,wherein the detector module has a photoresponsive means which possessesan output variable in response to the characteristics of the lightsupplied to the detector. The invention additionally providesmonochromator means as well as filter compartment means, each in aseparate module'for use in the system. The invention also provides abase unit for receiving and supporting such modules, for facilitatingalignment and adjustment thereof, and provides holder means for samplesand filters which holders are adapted to allow maximum versatilityinmanipulating and locating samples and filters with a maximum ofsimplicity and reliability.

The manner in which the invention achieves its objects will be morefully understood when considered in conjunction with a more completedescription of the preferred embodiments of the invention, and as shownin the drawings, in which like reference numerals indicate correspondingparts throughout.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showingthe arrangement of a typical instrument made with the modules of theinvention, including a power supply modules, a light source module, amonochromator module, a filter compartment module, a sample compartmentmodule and a detector module with a meter associated therewith;

FIG. 2 is a perspective view of the light source module of the presentinvention;

FIG. 3 is a vertical sectional view of the light source module of thepresent invention, showing fastening means thereon;

FIG. 4 is an isometric view of the monochromator module of the presentinvention;

FIG. 5 is a top plan view of the monochromator module of FIG. 4 with thetop cover thereof raised, and illustrating the interior componentsthereof;

FIG. 6 is a vertical sectional view, taken on lines 6--6 of FIG. 4,showing the monochromator module;

FIG. 7 is a vertical sectional view, taken on lines 7 7 of FIG. 4showing the monochromator module;

FIG. 8 is an isometric view of the sample compartment module of theinvention;

FIG. 9 is a top plan view of the sample compartment module of FIG. 8with the top cover thereof raised, and showing the holder unit therein;

FIG. 10 is a top plan view of the sample compartment module of FIG. 9showing the interior thereof with the sample holder removed therefrom;

FIG. 11 is an isometric view of the sample compartment module taken fromthe rear thereof; 7

FIG. 12 is a side view, partly in elevation and partly in section,showing the sample compartment module with the holder unit in placetherein;

FIG. 13 is a view, on an enlarged scale, of the cuvette and holder unitassembly of the invention, showing the cuvette element in an explodedrelation;

FIG. 14'is a top plan view of the holder unit of the invention;

FIG. 15 is a bottom plan view of the holder unit of the invention; 1

FIG. 16 is a vertical sectional view of the holder unit,

taken along lines 1616 of FIG. 14;

FIG. 17 is a vertical sectional view, taken along lines 17-17 of FIG.14;

FIG. 17a is an isometric view of a filter element of the invention;

FIG. 18 is an isometric view of the sample compartment light shield;

FIG. 19 is an isometric view of the detector module of the invention;

FIG. 20 is an electrical schematic view showing the power supply,photoresponsive detector means, amplifier and meter unit therefor;

FIG. 21 is a top plan view, showing certain portions of the base unitfor supporting some of the modules of the present invention;

FIG. 22 is a side elevational view of certain portions of the base ofunit shown in FIG. 21; 7

FIG. 23 is a vertical sectional view of the base unit, taken on lines23-23 of FIG. 21;

FIG. 24 is a diagrammatic view,'showing the operation of the modules ofthe present invention when assembled to form a spectrophotometer unit;

FIG. 25 is a diagrammatic view showing the modules of the presentinvention assembled to form a filter colorimeter;

FIG. 26 is a diagrammatic view showing the modules of the presentinvention assembled to form a nephelometer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawingsin greater detail, FIG. 1 shows an array 30 of modules disposed inposition to form a typical analysis instrument. FIG. 1 shows that suchan instrument may include a light source module 32, a monochromator unit34, a filter compartment module 36, a sample compartment 38, a detectormodule and a meter means 42, all of said instruments being attached to abase unit 44. A power supply module 46 is shown to furnish power to themeter 42, and to the detector module 40, and the power supply module 46also supplies power to the light source module 32.

LIGHT SOURCE MODULE Referring now to FIG. 2, the light source module 32is shown to include a housing 50, a cover element 52 held in place bythumb screws 54 and a mounting block 56 disposed on one side thereof.This mounting-block includes a cylindrical extensiontube 58, and has anopening 60 therein allowing passage therethrough of a fastener in theform of a mounting screw 62.

Referring now to FIG. 3, the structure of the mounting block 56 isshown, and FIG. 3 also shows that the mounting screw 62 contains knobmeans 64 on one end thereof, which is locked by a set screw 66 onto theshaft 68 of the screw 62. In addition, a condensing lens 70 is held inplace in a shoulder 72 in the tube 58, which in turn is mounted by a setscrew 74 in the mounting block 56. Thus, the cylinder and condenser lens58, 70 are disposed in registry with an opening 76in a side wall of thelight source module. FIG. 3 also shows the disposition of a mountingflange 78 which holds a bulb unit 80 in place, with the base thereofreceived in a socket 82.

In operation, it will be seen that the cylindrical tube 58 is adapted tobe placed in registry with a side wall I opening on an adjacent moduleunit, and manipulation of the knob 64 serves to hold the light sourcemodule locked in the desired position.

MONOCI-IROMATOR MODULE Referring now to FIGS. 4 through 7, themonochromator unit of the invention is shown. This unit includes housingmeans 84, a top cover unit 86, having a dial indicator opening 88, aknob opening through which a wavelength adjustment knob 92 protrudes,fastening means 48 on the front portion thereof, and hinge means 94enabling the top 86 thereof to be opened.

.As shown in FIG. 5, when the top cover 86 moves upwardly about the axisof the hinge 94, a transparent cover plate 96, made for example, ofpolymethyl methacrylate clear plastic material or the like is exposed,and this plastic cover plate 96 is supported by fasteners 98 carried byan inner frame unit 100. FIG. 5 shows means in the form of a wheel 102for indicating the wavelength of a light beam diffracted onto an exitslit 104 supported on an optical alignment frame 106, carried by theinner frame unit of the monochromator unit. A flange unit 108 isprovided for locating an indexing marker 110 thereon so thatcalibrations 112 on the wheel 102 may be aligned therewith to determinethe wavelength of light diffracted and propagated through the exit slit104 by the monochromator.

As best shown in FIG. 6, leg means 114 include a pair of rear cap screws116 extending therethrough in a position corresponding to that of theclamping screw 48. FIG. 6 also shows that the shaft 118, which includesthe knob 92 on the top thereof has the indexing wheel 102 attachedthereto by means of a collar 120. Shaft 118 extends through a shaftsupport bracket 122 equipped with means therein for journaling the shaft118. A cardioid profile cam 124 is fixedly attached, as by an integrallyformed collar 126, onto the shaft 118, and cam follower means in theform of an adjusting screw 128 has a base portion 130 thereof riding onthe outer surfaces of the cam 124. The adjusting screw 128 is held inplace by a lock nut 132 which secures it to the mirror support assembly134, while a coil helper urges the screw 128 into contact with the cam124.

The mirror support assembly 134 includes fasteners 136 holding a supportflange 138, which in turn holds themirror 140. Fasteners 142 areconnected to either end of a leaf spring 144, which connects one end ofthe support assembly 134 with a projection 146 forming a part of theoptical'frame 106.

The optical frame 106 includes a slotted holder 148 which supports afirst lens 150, a second lens 152, and diffraction means 154 in the formof a grating disposed between the lenses 150, 152. The exit collimatingslit 104 has a counterpart in the entrance collimating slit 156, each ofthe slits 104, 156 being fastened to the optical base 106 by flanges158. An entrance opening 160 is provided in alignment with the entranceslit 156, and

an exit slit 162 is provided which is in alignment with the exitcollimating slit 104; the lens unit 164 is placed just in front of theoutlet opening 162.

Although the operation of themonochromator unit just described isfurther discussed below, it can be seen that the mirror held on thesupport assembly 134 is adapted to be moved through an angle as the dial102 and the cam 124 associated therewith are rotated, and that, as aresult, light entering the entrance and passing to the slit 156 will bereflected at varying angles by the mirror.l40,thereby striking thediffraction grating 154 at different angles, with the result that a beamof light having a selected wave length will be focused on the exitcollimating slit 104, before passing through the exit lens 164 and theopening means 162 in the monochromator housing 84.

The cam 124, in a preferred embodiment, is in the general shape of acardioid, because the indicia 112 on the dial 102 are equally spacedapart or linearly calibrated. The cardioid cam profile results inaltering the angular change of the mirror from a non-linear function toa linear function,- the cardioid being a projection thereof on a flatsurface. The provision of the leaf spring 144 affords simplicity inoperation, and affords vertical stiffness, whereas the helper spring 135provides means for biasing the mirror support 134 against the cam unit124.

The optical base unit 106 provides a simple and inexpensive support andalignment means for the optical components held therein and attached tothe frame unit 100 and also serve to simplify the alignment of thesecomponents in respect to each other, especially during manufacture ormaintenance.

SAMPLE COMPARTMENT MODULE 180 has a counterpart or exit opening 182 onthe opposite side of the housing 166, as well as a third opening 184 onan end wall of the housing 166.

FIG. 11 also shows that a floor unit 186 is provided for rotatablysupporting a holder unit 188, the construction of which will bedescribed in detail below. Referring to FIGS. and 11, it is shown thatthe floor element 186 includes a circular opening 190 therein forremovably receiving the sample or filter holder unit 188. A spring unit192 having a point 194 protruding therefrom is secured by fasteners 196to the floor 186, anda light shield support bracket 198 havingvertically extending legs 200 is held by fasteners 202 onto the floorunit 186 of the sample compartment module 38.

Referring particularly to FIGS. 9 and 10, it can be seen that a shaft204 extends inwardly through the cover member 176 of the module 38, andthat the shaft includes a key 206 extending outwardly therefrom, the key206 being adapted to be received in a keyway slot 208 in the holder 188,to prevent relative rotation between the shaft 204 and the holder 188.Light excluding means in the form of a sponge rubber gasket 210 areprovided on the interior face of the cover unit 176, so that when thecover is lowered into position, extraneous light will not be allowed toenter the interior of the sample module 38. Referring again to FIG. 9,there is shown a hingedly mounted light shield unit '212, having acollimating slit 214 therein, as well as a side wall opening sheildmember 216, the purpose of which will be described in detail laterherein.

SAMPLE HOLDER UNIT shaft 220 of the holder 188 includes a keyway 208therein, as shown.

Referring now to FIGS. 12, 16 and 17, it can be seen that a plurality ofcompartments 226 are provided for removably receiving light transmittingelements, in this case, sample holder cuvettes 218, therein, andthesecompartments 226 are made up of inner walls 228, outer walls 230, andbottom support walls 232. Both the inner and outer walls 228, 230 haveflanges 234 on the ends thereof, the flanges 234 being spaced apart fromeach other. In addition, a slot 236 extends at least partiallydownwardly of the outer wall portion 230. The inner edges of the flanges234 serve to define partial, spaced apart side walls 238 disposed atright angles to the inner and outer walls 228, 230. Thus, a cuvette unit218 may be received in a holder unit 188, and the flanges 234 willoverlap the edge portions of the euvette 218 sufficiently to lock thesame in place but in a manner so that apertures'226 extending betweenthe faces 240 of the flanges 234 will allow passage of lighttherethrough. I

In operation, a plurality of cuvettes 218 are disposed in positioninside the holders 188, and thereafter, the holder 188 is positionedwith the cylindrical extension 222 thereof fitted snugly but slidinglyinto the opening 190 of the floor 186 of the sample compartment 38.Thereafter, when the cover 176 of the module 38 is closed, the key 206engages the keyway 208 in the shaft 220 of the holder, and rotation ofthe knob 172 rotates the cuvette holder 188 successively into aplurality of positions with the apertures 226 formed between the faces246 of the flanges being aligned with the pairs of openings 180, 182 inthe housing portion 166 of the module 38. Thus, a beam of lightpropagated therethrough will pass through the cuvette holder and anysample liquid contained therein, and out the other opening, in order tohave the intensity or other characteristics thereof respondedto bythedetector means placed adjacent thereto.

The detent means in the form of notches 224 cooperate with the spring192 and the point thereon so that the holder 188 is indexed into thedesired position allowing passage of light therethrough. The provisionof the extra detent notch 242 (FIG.' 15) is made so thatinitial readingsmay be taken when no light is allowed to be transmitted between theopenings 180, 182. Thus,

referring to FIG. 11, it is shown that the holder 188 is in such aposition, that it in the case of a holder having four compartments, at a45 angle with respect to any one of its normal locked-in positionsspaced apart.

Referring now to the dimensions of the unit 188, relative sizes are notcritical, except that in some cases, referring to the outer walls 230,and the provisions of the slots 236 therein, it is desired that thethickness of the material comprising the walls 230 exceeds the width ofthe slot 236, so that when the holder 188 is placed in the 45 anglepositionreferred to above, no light can pass through this slit, since,in this orientation, the slit itself is deeper than it is wide.

Nevertheless, as will appear more fully herein, it is desired to have aslit in the position shown, since it is desired to direct a light beamtherethrough when the sample compartment is used as a nephelometer,whereas it is desired to exclude light therefrom when the holder 188 isbeing used as a part of a spectrophotometer and is in the position shownin FIG. 11. Thus, the holder unit. shown has a number of noveladvantages and characteristics which render it particularly suitable foruse in a modular system of the type shown. In addition to the zero lighttransmission setting for a 45 position referred to above, the additionaldetent notch 242 provides a convenient method of allowing the indexingof the exterior knob 172 so that if a consecutive plurality of samplesis desired to be analyzed, the process is facilitated because there isalways a ready reference mark provided for locating the relativeposition of the first sample.

Another advantage of the holding unit just described is that thisconstruction facilitates the interchange between cuvetteunits 218 andoptical filter units 244, such as those shown in FIG. 17a.

FILTER COMPARTMENT MODULE light shield unit 212 and the end wallopening'l84 need not be provided. Otherwise, the only difference betweenthe filter unit and the sample compartment unit resides, not in theconstruction of these units, but in the type of insert placed in thecompartments 226 of the holder 188, the indicia printed on the cover,and other portions not novel in themselves.

Thus, referring to FIG. 17a there is shown a light emitting filterelement 244, of a generally rectangular LIGHT SHIELD Referring now toFIG. 18, the light shield assembly 212 is shown in greater detail. Itcan be seen that this unit includes the slit 214 described above, andtheside wall opening shield 216, and that pivot points in the form of smallprojections 254 are provided for engagement with corresponding openingsin the vertical legs 200 of the flange 198. The significance of thisshield unit and the manner of its functioning will be described furtherherein.

DETECTOR MODULE Referring now to FIG. 19 and 20, FIG. 19 illustrates thedetector module 40 and FIG. 20 is a simplified schematic illustration ofthe operations of this unit. As shown in FIG. 19, the housing means 256of the detector 40 includes an opening 258 therein for receiving a lightbeam, and this unit also includes a reference knob adjustment 260, ablank" adjustment knob 262 and a zero adjustment knob 264, as well astwo binding parts 266, for receiving electrical connectors. At thebottom of the housing 256 of the detector module 240 are disposed legelements 268, the front leg being shown to include a removal and lockingscrew means 270.

The function of the detector module is to receive en ergy from the powersupply unit 46 shown in FIG. 1, and from the light source module 32, andto use the power supply energy to amplify the energy received in thedetector from the light source for display on means such as the metershown at 42 in FIG. 1. The manner in which this is carried out, will beset forth below.

Referring now to FIG. 20, there is shown a power supply unit 272, aphotodiode 274, amplifier means 276, and display means 278 in the formof a meter, recording potentiometer and pen, or the like.

In a preferred embodiment, 115 volt alternating current is supplied fromthe plug 280, through two leads 282, to a primary winding 284 which isinductively coupled through a permeable core 286 to secondary windcoilsand additional capacitors may be provided. At junction 296, voltspositive polarity DC is impressed, and a dropping resistor 298 providesten volt positive potential at the junction 300, which is impressed onone terminal 302 of the photodiode 274. A further dropping resistor 304is connected through a junction 306 to the ground 308.

The secondary winding 290 is tapped to provide six volts of alternatingcurrent for heating the filaments 310 of the amplifier means 276, whichis preferably in the form of a selected and aged so-called duo-triodetube, such as a 12AU7A tube. The other terminal 312 of the photodiode274 is connected,'through a reference potentiometer 314 to a gridresistor 316 connected to one grid 318 of the amplifier 276, while theother grid 320 of the amplifier 276 is connected through a' resistor 322to ground at 308. A capacitor 324 is placed in the lead 326 whichconnects the two grids 318, 320, preventing flow of direct currenttherebetween. Both plates 32 8, 330 of the amplifier 276 are connectedat the junction 296 to the 90 volt positive DC plate potential. A secondterminal 332 attached to the secondary winding 288 connects a 40 voltnegative potential, through a resistor 334, to a zeroing potentiometer336, which serves as a voltage divider between two cathode resistors338, 340. Thus, adjustment of the zero adjustment or potentiometeralters the voltage on the two cathodes 342, 344, of the common amplifier276. The display means in the form of a meter 278 is connected acrossthe output of the resistors 338, 340.

A third potentiometer 346 is connected to one terminal 312 of thephotodiode through a resistor 348, and through .a resistor 350 to aterminal which also receives the 40 'volt negative DC potential. Thispotentiometer 346 is the blank adjusting potentiometer.

In operation, it may be seen that as electronic energy in the form ofphotons is directed to and all on the photo-tube, it emits electrons inresponse to the intensity of the incident beam, and becomes more or lessconductive, and current flowing 'therethrough is fed through thepotentiometer 314, inpressing a given voltage onto the grid 318 of theamplifier tube 276. As a bias is impressed on the grid 318 which difersfrom the bias impressed on the grid 320, which is held at a constantpotential, it is obvious that more current will tend to flow from thecathode 342 to the plate 328, than from the cathode 344 to the plate330. The differeing potential thus establishes .the relative amounts ofcurrent flowing in each electrode pan, and this will be reflected in thereading of the meter 278, since some current will tend to from theoutput of the resistor 340 through the meter 278 to the plate 328 aswell as to the plate 330, if the path thereby established offers lessresistance, by reason the bias palced on the grid 3 18. The

. zeroing potentiometer 336 is adjusted so that when little or notcurrent is flowing in the phototube circuit, the inter-electroderesistance between the pairs of cathode-plate connections 342, 328 and344, 330 is the same.

Thus, the function of the 12AU 7A tube is that of receiving the signalor varying voltage from the phototube across one grid thereof, andmodulating the current flowing in one of the cathode-to-plate circuitsof the tube 276. When such current difference is measurable, a readingis obtained on the meter 278, which is connected across to the cathodes342, 344.

In place of the meter 278, which is ordinarily a 200 microampere meter,a recording potentiometer or the like may be inserted, suitablyconnected, as is well known to those skilled in the art.

The reference potentiometer is used to adjust the circuit for the effectof placing a so-called reference cuvette in the sample compartment inthe path of the light. In this way, setting the meter at a value of100.0 gives a proper reference for other readings.

The zero potentiometer adjustment balances current flow in the cathodeplate circuits and creates zero current in the meter when the light pathto the detector is blocked.

The blank potentiometer is not used in colorimetric orspectrophotometric measurements, but may be adjusted to alter theconductance or threshold of the photodiode. Since this potentiometer andthe reference potentiometer are in parallel, adjustment of one affectsthe preset as desired before adjusting the reference potentiometer.

Referring now to FIGS. 21-23, the base unit 44 is shown, and this unitincludes a generally flat top surface portion 351, a plurality of rubberleg units 352 supported by fasteners 354 extending through the topsurface 350 thereof. These views show that somewhat inclined ramp units356 are provided for either end of thebase unit 44 to facilitate placingmodules thereon and removing them therefrom. It can also be seen,particularly in reference to FIG. 23, that the side wall portions 358which engage the adjusting and mounting screws are tapered, and thisconstruction serves to assure that the module supported on the base willnot only be aligned, but will be moved vertically into a closelyoverlying position in relation to the top surfaces 351 of the base 44.

The base 44 is sufficiently long to allow room for all the modulesdescribed above to be disposed in the varying relations to be furtherdescribed below.

Referring now to FIGS. 24 through 26, inclusive, these diagrammaticviews illustrate the manner in which various optical analyticalinstruments may be made by assembling the modules of the presentinvention in various combinations.

Thus, referring to FIG. 24, it is diagrammatically shown that the lightsource module 32, is attached to the side wall surface of themonochrometer 34, so that the bulb unit or light source means 80 isdirected through the lens 70 and through opening means 160 in the sidewall of the monochrometer 34, and is propagated through the entranceslit 156. Thereupon, the light beam is reflected from the movablymounted mirror 140 through the lens 150 and onto the diffraction grating154, before being focused by the lens 152 onto the collimating exit slit104, from where it is propagated through the exit lens 162. Thus,movement of the mirror changes the angle of incidence of the light raysfalling on the diffraction grating 154, and the portion of the spectrumthus created is moved in relation to the slit 104. The monochromaticbeam thus generated, in a preferred embodiment of the invention, has aband width of approximately 20 millimicrons, which is sufficientlynarrow for precise analytical work.

This beam is condensed on lens 162, whereupon the output of themonochromatic beam is then directed through a cuvette. or like sampleholder means 218 which is located between the openings 180, 182 in theside wall portions 166 of the sample compartment 38.

Since FIG. 24 is a diagrammatic view, only a'single cuvette 218 is shownand the size thereof is represented as being relatively larger. The beamemerging from the sample compartment 38 is directed through the openingmeans 258 in the detector module 40, and then directed to the photodiodetube 302, or other suitable means which are electronically responsive tolight energy falling thereon. The detector module is shown schematicallyto include an amplifier 276 and a potentiometer means 334. The outputfrom the amplifier unit 276 is directed to the visible display means inthe form of a meter 42, which, as pointed out, reads in proportion tothe current shunted from one cathode of the amplifier tube to the othercathode.

Referring to FIG. 25, it is shown that the light source module 32,including the filament 80 and condensor lens 70, are disposed with theopening in the fube 58 facing an opening in the filter compartment 36,which contains one or more filter elements 244. The output is thendirected through the two openings 180, 182, in the sample compartment38, and thus through a sample held in the cuvette 218. The lightstriking the photodiode 302 causes-unbalanced current flow in theamplifier 276, and the amount of current flow is reflected in thereading displayed on the meter 246..This engagement of the modulesproduces a filter colorimeter wherein the light source, the filter andsample compartments 36, 38, and the detector means 40 are all in aparallel alignment. As pointed out above, filter elements 244 havingdifferent filter lenses 250 therein are generally moved successivelyfrom position to position, and the resulting readings are then plottedgraphically.

' source module 32, the sample container 38, detector module 40, andmeter means 42, is illustrated in which the instrument formed is anephelometer.

In this arrangement, the photo tube 302 of the detector 40, impresses avoltage on one grid-of the amplifier 276 in proportion to the lightscattered by a sample held in the cuvette 218, when the light is fedthrough a slit 214 in the light shield 212, and through a slot 236 inthe holder 188, from the container lens module 32. This voltage resultsin current flow through the meter 42, as pointed out above.

As is well know, nephelometry relates to the measurement of lightscattered at right angles to an incident beam by collidal or other fineparticles suspended in the solution.

This method is somewhat similar to turbidimetry, that is, measurement oflight passing directly through a sample having agglomerated particlestherein.

Thus,.the above illustrations show the capacity of the modular system toform a number of different analytical instruments from modules whichsimplify teaching of theories and operational principles by reason oftheir invention may be made by those skilled in the art with outdeparting from the spirit of the invention or the scope of the appendedclaims.

l claim:

1. A holder unit for use in an optical instrumental analysis system,said holder unit being adapted to re movably receive a plurality ofsimilar light transmitting inserts therein, and comprising, incombination, means for rotatably supporting said unit in a desiredposition on a support member, means for registering said holder in adesired position; means in said holder unit for receiving drive meansfor rotating said holder unit, and

means defining a plurality of compartments for receiving said lighttransmitting elements therein, said means comprising, for eachcompartment, inner wall means having outwardly extending spaced apartflanges at the ends thereof, outer wall means having inwardly extendingspaced apart flanges at the ends thereof, bottom support wall meansextending outwardly from the lower portion of said inner side wallmeans, the facing edges of said flanges defining, in combination, a pairof partial side wall portions spaced apart from each other, and defininga pair of apertures therebetween for allowing a beam'of light to bepropagated therethrough.

2. A holder unit as defined in claim 1 which further includes aplurality of similar generally rectangular cuvette means removablyreceived in said compartments, whereby rotation of said holder about afixed axis will successively move each 'of said cuvette means so heldinto the same position relative to a stationary light beam directedthrough one of said pairs of apertures.

3. A holder unit as-defined in claim 1 which further includes aplurality of similar, generally rectangular color filter units removablyreceived in said compartments, each of said filter units having anaperture extending therethrough with an optical filter disposed in saidaperture, whereby rotation of said holder about a fixed axis willsuccessively move each of said filter units so held into the sameposition relative to a stationary light beam directed through one ofsaid pairs of apertures.

4. A holder unit as defined in claim 1 in which said means in saidholderunit for receiving drive means for rotating said holder unitcomprises a centrally disposed shaft member having a keyway therein.

5. A holder unit as defined in'claim 1 wherein said holder unitcomprises a one piece unit integrally formed from a molded ocetalpolymeric synthetic resinous material.

6. A holder unit as defined in claim 1 which includes a plurality ofcuvette units removably received in said holder, and in which said inneredges of said flanges defining said side wall portions are of a lengthsubstantially equal to the length of said cuvettes.

7. A holder unit as defined in claim 1 in which said means for rotatablysupporting said holder unit in a desired position in a samplecompartment comprises a cylindrical boss extending downwardly from saidholder unit, said boss being adapted for reception in an opening in saidsample compartment.

8. A holder unit as defined in claim 1 in which said means in saidholder unit for receiving drive means comprises registrationmeans, andwhich further includes knob means having indicia thereon for indicatingthe relative position of said holder.

I UNITED STATES PATENT OFFICE 7 CERTIFICATE OF CORRECTION P tent No.3,806,259 I Dated April 23, 1974 Inuentofls) Roy E. Boostrom et a1.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown'below:

Column 1, line 18, "694,417" should read --694, 5l7- Column 3, line 61,"modules" should read -module-- Column 12, 1ine'l2, after "reads" insert--out- I Signed and sealed, this 1st day of October 1974;

(S Attest:

MCCOY M, GIBSON JR. c. MARSHALL DANN I Attesting Officer Commissioner ofPatents F ORM PC4050 (IO-69) USCOMM-DC 60376-P69 a u.s. aovllumim' nmmm:ornc: 1 m1 o-rsss-azu,

1. A holder unit for use in an optical instrumental analysis system,said holder unit being adapted to removably receive a plurality ofsimilar light transmitting inserts therein, and comprising, incombination, means for rotatably supporting said unit in a desiredposition on a support member, means for registering said holder in adesired position; means in said holder unit for receiving drive meansfor rotating said holder unit, and means defining a plurality ofcompartments for receiving said light transmitting elements therein,said means comprising, for each compartment, inner wall means havingoutwardly extending spaced apart flanges at the ends thereof, outer wallmeans having inwardly extending spaced apart flanges at the endsthereof, bottom support wall means extending outwardly from the lowerportion of said inner side wall means, the facing edges of said flangesdefining, in combination, a pair of partial side wall portions spacedapart from each other, anD defining a pair of apertures therebetween forallowing a beam of light to be propagated therethrough.
 2. A holder unitas defined in claim 1 which further includes a plurality of similargenerally rectangular cuvette means removably received in saidcompartments, whereby rotation of said holder about a fixed axis willsuccessively move each of said cuvette means so held into the sameposition relative to a stationary light beam directed through one ofsaid pairs of apertures.
 3. A holder unit as defined in claim 1 whichfurther includes a plurality of similar, generally rectangular colorfilter units removably received in said compartments, each of saidfilter units having an aperture extending therethrough with an opticalfilter disposed in said aperture, whereby rotation of said holder abouta fixed axis will successively move each of said filter units so heldinto the same position relative to a stationary light beam directedthrough one of said pairs of apertures.
 4. A holder unit as defined inclaim 1 in which said means in said holder unit for receiving drivemeans for rotating said holder unit comprises a centrally disposed shaftmember having a keyway therein.
 5. A holder unit as defined in claim 1wherein said holder unit comprises a one piece unit integrally formedfrom a molded ocetal polymeric synthetic resinous material.
 6. A holderunit as defined in claim 1 which includes a plurality of cuvette unitsremovably received in said holder, and in which said inner edges of saidflanges defining said side wall portions are of a length substantiallyequal to the length of said cuvettes.
 7. A holder unit as defined inclaim 1 in which said means for rotatably supporting said holder unit ina desired position in a sample compartment comprises a cylindrical bossextending downwardly from said holder unit, said boss being adapted forreception in an opening in said sample compartment.
 8. A holder unit asdefined in claim 1 in which said means in said holder unit for receivingdrive means comprises registration means, and which further includesknob means having indicia thereon for indicating the relative positionof said holder.